Authentication

Can anybody help? I am an admin. Is there anyway for an Admin to add an User Id and Password and generate ID to make make sure they are not duplicate and send an auto e-mail based on e-mail given by the user? I know they can go in and change the Password. How can an admin generate an ID and PW and enter Names etc. and e-mail to the user for the first time? If any body can help me I shall truly appreciate. DD